1. Field of the Invention
The present general inventive concept relates to a front surround sound reproduction system using a speaker array, and more particularly, to a front surround sound reproduction system improving the performance of beam steering by using a speaker array which is arranged geometrically on two or more planes or on one curved surface, and a signal reproducing method for the system.
2. Description of the Related Art
In general, a front surround sound reproduction system utilizes sound projection technology, thereby generating a stereo effect by using a speaker array on a front surface without side or back speakers.
The front surround sound reproduction system uses the speaker array to generate a sound beam from a surround channel signal, and by steering the sound beam 30 degrees or more, generates a stereo effect through wall reflection. Accordingly, due to the reflected sound, a listener feels a stereo effect as if the sound came from side and back speakers.
Technology related to this front surround sound reproduction system is disclosed in WO 04/075601, filed Sep. 2, 2004, entitled “A Sound Beam Loudspeaker System”.
FIG. 1 is a diagram illustrating a front surface part 100 of a speaker of a conventional front surround sound reproduction system.
The front surface part 100 of the speaker includes a speaker array 111 reproducing a high frequency signal and a woofer 112 reproducing mid and low frequency signals.
Accordingly, the front surround sound reproduction system divides an input surround channel signal into a high frequency signal and a mid and low frequency signal, and provides the high frequency signal to the beam forming speaker array 111, and the mid and low frequency signal to the woofer 112.
The speaker array having one plane as illustrated in FIG. 1 forms a beam which can be twisted at a variety of steering angles in relation to the front of a listener when a signal of each channel is generated. In this case, the steering angle is the angle between a vector perpendicular to the speaker array surface and the directional vector of the beam. For example, as illustrated in FIG. 1, the speaker array on one plane generates a center channel (C) beam twisted by 0 degrees, a left surround channel (Ls) and a right surround channel (Rs) beams twisted by 30 degrees, and a left front channel (L) and a right front channel (R) with beams twisted by 60 degrees. However, when a beam is projected at an angle of 30 degrees or more, it generally has a lowered sharpness. Thus, if the steering angle of a sound beam increases, the effective aperture of a speaker array decreases, thereby lowering the beam performance.
According to conventional technology, when a surround channel signal is reproduced in the speaker array structure, the projected beam is twisted by 70-80 degrees. Thus, the quality of the beam is lowered and it fails to provide the intended stereo sound effect.